Fluorenone

About: Fluorenone is a research topic. Over the lifetime, 1067 publications have been published within this topic receiving 17162 citations. The topic is also known as: Diphenylene ketone & 9-Oxofluorene.

Electronic and Vibrational Properties of Fluorenone in the Channels of Zeolite L

Abstract: Fluorenone (C13H8O) was inserted into the channels of zeolite L by using gas-phase adsorption. The size, structure, and stability of fluorenone are well suited for studying host–guest interactions. The Fourier transform IR, Raman, luminescence, and excitation spectra, in addition to thermal analysis data, of fluorenone in solution and fluorenone/zeolite L are reported. Normal coordinate analysis of fluorenone was performed, based on which IR and Raman bands were assigned, and an experimental force field was determined. The vibrational spectra can be used for nondestructive quantitative analysis by comparing a characteristic dye band with a zeolite band that has been chosen as the internal standard. Molecular orbital calculations were performed to gain a better understanding of the electronic structure of the system and to support the interpretation of the electronic absorption and luminescence spectra. Fluorenone shows unusual luminescence behavior in that it emits from two states. The relative intensity of these two bands depends strongly on the environment and changes unexpectedly in response to temperature. In fluorenone/zeolite L, the intensity of the 300 nm band (lifetime 9 μs) increases with decreasing temperature, while the opposite is true for the 400 nm band (lifetime 115 μs). A model of the host–guest interaction is derived from the experimental results and calculations: the dye molecule sits close to the channel walls with the carbonyl group pointing to an Al3+ site of the zeolite framework. A secondary interaction was observed between the fluorenone's aromatic ring and the zeolite's charge-compensating cations.

Understanding the Nature of the States Responsible for the Green Emission in Oxidized Poly(9,9‐dialkylfluorene)s: Photophysics and Structural Studies of Linear Dialkylfluorene/Fluorenone Model Compounds

Abstract: Here, the optical properties of a series of structurally well-defined model compounds for oxidatively degraded poly(dialkylfluorenes) (PFs) are reported. Specifically, linear compounds comprising one, two, or four dihexylfluorene (F) moieties together with one fluorenone (O) moiety placed either at the end or in the center of each chain (i.e., FO, FFO, FOF, FFOFF) are studied. The results support the recent observation that the photophysics of the fluorenone-centered "pentamer" (FFOFF) is most similar to that of oxidized PFs. They further demonstrate that molecule―molecule interaction is essential to activate the green emission band. Investigations by X-ray diffraction (XRD) identify the solid-state structure of a representative member of this class of compounds and reveal inter-molecular interaction through dipole―dipole coupling between neighboring fluorenone moieties.

Regiochemically well-defined fluorenone-alkylthiophene copolymers: Synthesis, spectroscopic characterization, and their postfunctionalization with oligoaniline

Abstract: A new solution processable, regioregular, alternate copolymer of fluorenone and dialkylbithiophene, namely poly[(5,5‘-(3,3‘-di-n-octyl-2,2‘-bithiophene))-alt-(2,7-fluoren-9-one)] (abbreviated as PDOBTF), was synthesized by three different preparation methods: chemical or electrochemical oxidation of 2,7-bis(4-octylthien-2-yl)-fluoren-9-one or polycondensation of 2,7-bis(5-bromo-4-octylthien-2-yl)-fluoren-9-one in the presence of Ni(0) reagent. Independent of the preparation method, the crude product is a mixture of high molecular weight fractions and short oligomers. It can be however easily fractionated into fractions differing in their molecular weight by sequential extractions with a series of solvents. The principal absorption band registered for the undoped polymer (λmax = 384 nm for the THF solution and 389 nm for the solid state) originates from the π−π* transition of the conjugated backbone and is blue-shifted because of the chain torsion effects caused by steric hindrance. This band is accompani...

Reversible luminescence color switching in the crystal polymorphs of 2,7-bis(2′-methyl-[1,1′-biphenyl]-4-yl)-fluorenone by thermal and mechanical stimuli

Abstract: Smart organic luminescence materials that exhibit a reversible stimuli-responsive change of luminescence color in the solid state without changing the chemical structure of their component molecules have attracted increasing interest. We employed the design strategy of introducing different weak interactions into the same molecular system to synthesize 2,7-bis(2′-methyl-[1,1′-biphenyl]-4-yl)-fluorenone (MPF). Two crystal polymorphs of MPF, green-yellow crystal G-MPF and orange crystal O-MPF, were obtained through culturing the single crystal under the different crystallization conditions of diffusing diethyl ether into its respective tetrahydrofuran or CH2Cl2 solution. Both of the two crystal polymorphs exhibit high luminous efficiency and reversible stimuli-responsive solid-state luminescence color switching. Upon heating the green crystal G-MPF or grinding the orange crystal O-MPF, their emission reversibly changes between green at 530 nm and orange at 570 nm. The X-ray single-crystal structures, characterization of the photophysical properties, powder X-ray diffraction and differential scanning calorimetry provide insight into the phase transformation and the luminescence behavior. The results indicate that the green emission of G-MPF originates from molecular J-aggregation and the orange emission of O-MPF originates from static excimers. This work discusses the relationship between the molecular stacking mode and the photophysical properties, and demonstrates a molecular design strategy to obtain stimuli-responsive organic solid-state luminescence switching materials.